Flashcards in Endocrine System & Diseases Deck (118)
What is autocrine signaling?
Signaling within the cell
What is paracrine signaling?
Signaling between local cells
What is endocrine signaling?
Between remote cells
What are some general characteristics of hormonal function/regulation?
-specific rates and rhythm of secretion
-operate within feedback systems
-only affects cells with appropriate receptors to initiate specific functions
-either excreted by kidney or metabolized by liver
What are the 3 mechanisms involved in the regulation of hormone release?
Chemical factors (blood sugar, calcium levels), endocrine factors (hormone from one gland controlling another gland), neural control
Identify and explain the most common type of feedback system.
Negative feedback system: plasma levels of one hormone influence the plasma levels of another hormone
Explain the negative feedback system involved in the hypothalamic-pituitary-adrenal axis.
Normal hormone release is as follows... Hypothalamus secretes corticotropin releasing hormone (CRH).... Triggers release of adrenocorticotropic hormone release by the anterior pituitary... Cortisol levels increase...
When they exceeds a certain plasma level the negative feedback system triggers the hypothalamus to stop releasing CRH
Are peptide and protein hormones water or lipid soluble? What effect does this have on a hormone?
Peptide/Protein hormones are water soluble...and circulate in free/unbound form (only unbound hormones can affect the target site)
Lipid soluble hormones are primarily circulated bound to a carrier or protein (only small % are unbound)
Where are hormone receptors located and how do water soluble and lipid soluble hormones bind?
They are located on plasma membrane or in intra cellular compartments of the target cell; water soluble hormones bind to receptors on the cell membrane, while lipid soluble hormones (such as steroid hormones) easily diffuse across the cell membrane and bind either cytosolic or nuclear receptors
Does the pancreas function as an endocrine system... Or as an exocrine system?
Both!: as an endocrine system it secretes insulin, glucagon, somatostatin, and pancreatic polypeptide
As an exocrine system it is composed of acinar cells that secretes enzymes and networks of ducts that secrete alkaline fluids with digestive functions (80-85% of the pancreas)
The alkaline juices neutralize acidic chyme that enters the duodenum from the stomach and facilitates absorption of fat in the intestine
What is secreted from the alpha and beta cells of the pancreas?
Alpha cells secrete glucagon, beta cells secrete insulin
What is the primary cause of acute pancreatitis?
Gallstones and heavy alcohol use are responsible for 60-80%; other causes include infection, trauma, surgery, metabolic disorders (hypercalcemia, hyperlipidemia), some meds (flagyl, tetracycline, ace inhibitors, corticosteroids)
What is the primary cause of damage during periods of inflammation of the pancreas?
Digestive enzymes become activated before entering the duodenum and begin attacking the pancreas
What is acute necrotizing pancreatitis?
A severe form of pancreatitis characterized by necrosis and subsequent infection
Inflammation leads to necrosis which will typically become infected by gram negative bacteria in the alimentary tract..... Tissues become infected (acinar, ductal, islets of L).... Vascular injury can lead to massive hemorrhage within the pancreas
What is the primary signs, symptoms, and patho of acute pancreatitis?
Midepigastric pain radiating to the back, n/v, abdominal distention, tetany (from hypocalcemia), fever, paralytic ileus, hypoxemia
Injury or disruption of acinar cells permits leakage of pancreatic enzymes---- breaks down tissue and cell membranes--- causes inflammation, edema, vascular damage, necrosis....
What is the hallmark sign used for diagnosis of acute pancreatitis?
Elevated serum amylase level; but serum lipase is more specific and sensitive for the diagnosis of AP
What are the normal values for serum amylase and serum lipase?
3 times normal with acute AP
What is the goal of treatment for acute pancreatitis?
Stop auto digestion and prevent systemic complications
Aggressive fluid administration, Demerol over morphine (< sphincter of oddi spasm), bowel rest (NGT and TPN), h2 blocker, stone removal, antibiotics if necrotizing, surgery (ERCP, surgical debridement)
What is the patho and primary causes of chronic pancreatitis?
Chronic alcohol, smoking, obstruction from gallstones, autoimmune, obesity, genetic mutations
Toxic metabolites and chronic release of cytokines contribute to destruction of acinar cells and islets of langerhans----> fibrosis structures, calcification, ductal obstruction, pancreatic cysts
What are the signs and symptoms of chronic pancreatitis? Preventative measures?
Abdominal pain (continuous or intermittent), weight loss, DM, steatorrhea (pooping excess fat d/t decreased absorption)
Lifestyle modification, fat free diet, enzyme replacement, surgical drainage or resection
What are some anesthetic considerations for patient with pancreatitis?
Consider RSI (aspiration), fluid and electrolyte disturbance, monitor glucose, check Coags, pulmonary assessment, monitor renal function (UOP > 0.5 ml/kg/hr
What 3 physiologic processes do thyroid hormones have the most profound effects?
Growth, development, metabolism
Explain the primary characteristics of T3 and T4. Compare and contrast.
T3 is primary made during the conversion of T4 at the target tissues. It only comprises 10% of the circulating thyroid hormone but is responsible for 80% of the metabolic activity due to its high potency.
T4 is secreted by the thyroid and makes up 90% of the circulating thyroid hormone.
Explain the regulation of thyroid hormone.
Stimulus such as hypothermia causes the hypothalamus to secrete thyrotropin releasing hormone (TRH) which signals the thyrotropic cells of the anterior pituitary to secrete thyroid stimulating hormone (TSH)..... TSH causes follicular cells of the thyroid to release thyroid hormone....TH stimulates target cells to increase metabolic activity, resulting in an increase in body temperature..... Increased temperature is detected by the hypothalamus which discontinues release of (TRH).... TH also blocks the ability of TRH to interact with the anterior pituitary gland to prevent TSH formation..... This is a type of negative feedback system
The ability of the thyroid to have normal quantities of thyroid hormones depends on what source?
What are normal serum TSH levels?
0.5-5 mu/L; small changes in thyroid function causes significant changes in TSH; single best test of thyroid hormone action at the cellular level
What are some signs and symptoms of hypothyroidism?
Weight gain, cold intolerance, muscle fatigue/weakness, constipation, depression, decreased CO, SV, HR, contractility
What is the concern with severe hypothyroidism?
Myxedema coma... From extreme hypothyroidism.... Impaired mentation, hypo ventilation, CHF, hypothermia
When is it appropriate to place a PA catheter for resection of a pheochromocytoma?
In presence of CHF or decreased cardiac reserve; monitor pulmonary capillary wedge pressure